Burglar alarm system



Jan. 12, 1965 G. M. CALLAHAN 3,165,727

BURGLAR ALARM SYSTEM Filed April 24, 1962 2 Sheets-Sheet 1 INVENTOR GERARD CALLAHAN ATTORNEY.

FIG. v2.

Jan. 12, 1965 G. M. cALLAHAN BURGLAR ALARM SYSTEM Filed April 24, 1962 INVENTOR GERARD CALLAHAN BY xfuv@ ATTORNEY.

United States Patent 3,165,727 BURGLAR ALARM SYSTEM Gerard M. Callahan, Flushing, NSY., assiwor to Electrolert Inc., Il'amaica, NX. Filed Apr. 24, 1962, Ser. No. 189,903 1 Claim. (Cl. 340-274) This invention relates to alarm mechanisms. More particularly, this invention relates to alarm mechanisms for use in monitoring and announcing unauthorized movement of a movable member such as a door or the like.

The principal purpose of my invention is to provide an improved, unitary alarm mechanism for use at the location of a movable member such as that mentioned.

Another purpose of my invention is to provide an integral, self-contained alarm mechanism which is independent of external electric circuits.

Another purpose of my invention is to provide an electrically operated alarm mechanism which may be disabled only by selected authorized persons.

Still another purpose of my invention is to provide an alarm mechanism of the type indicated which will operate to sound an alarm even though the movable member is immediately restored to its proper position.

According to an embodiment of my invention, I provide an alarm mechanism which is assembled and supported in a case. The embodiment has a source of voltage inside the case to which the electrical components are connected. lt has a tripping mechanism which is adapted to initiate the alarm sounding sequence by closing a rst or tripping circuit in response to movement at the member.

The tripping circuit of the embodiment is provided with two series connected switches both of which must be closed in order for the circuit to become energized. One of the switches is adapted for manual operation by turning a key. The other of the switches has means adapted to be engaged by the tripping mechanism so that it is held open when the alarm is set for operation. The other switch also has a biasing spring engaging the switch contacts so that when the `tripping mechanism is released by movement at the member, the switch closes which, when the manual switch is also closed, initiates the alarm sequence.

A magnetic relay is provided in the case with its coil connected in the tripping circuit. It has a pair of normally opened contacts connected in shunt across the second switch mentioned so the tripping circuit is held closed by the coil, irrespective of the subsequent position of the second switch, whenever the coil is once energized. This holding action provides for irreversiblity in the alarm sequence so that the alarm sounds even though the movable member such as, for example, a wall panel, is rapidly restored to its proper position after an unauthorized openmg.

A second or time delay circuit is also provided so `that the alarm need not be sounded by persons who have proper authority to move the member. A time delay of, say, ten seconds, may therefore be provided during which time such persons are able to open the manual switch with their key to stop the alarm sequence. The magnetic relay is provided with a second pair of normally opened contacts which are connected in the time delay circuit. A time delay relay is also provided in this circuit so that when the coil in the tripping circuit is energized and the second pair of normally opened contacts is also closed, the timing period commences.

A third or alarm circuit is provided in which an an- .nunciator means such as bell is connected. The time delay relay has a pair of .normally opened contacts which are connected in the alarm circuit so that after the timing Y lbl? Patented Jan. l2, 1965 continues until someone such as a night watchman who has a key arrives at the scene and turns it off by opening the manually operated switch in the tripping circuit.

These and other features of my invention are described in detail in the following portion of the specication.

In the description which follows, reference is made to the accompanying drawings in which:

FIGURE l is an end view of an embodiment of my invention.

FIGURE 2 is a top view, partially broken away, of the embodiment of FIGURE l.

FIGURE 3 is a bottom view, partially broken away, of the embodiment of FIGURE 1.

' FIGURE 4 is a side view of the embodiment of FIG- URE 1. l

FIGURE 5 is a wiring diagram of the electrical circuits or the embodiment of FIGURE l. l

FIGURE 6 is a schematic diagram showing a general electrical arrangement for my invention.

An embodiment of my invention is shown in the drawings, note FIGURES 1e4, mounted in a case 10. The entire alarm mechanism of this embodiment is supported in this case so that it may be readily installed, as a unit, for operation. It has an electrically operated bell 11 which rings when the alarm is set off. A manually operated switch 12 is provided for turning the alarm on and offf Switch 12 has a lock type mechanism which can be operated only by insertion and turning of a key 13 so that only those persons having a key are able to control the alarm. Other types of manually operated switches Imay, of course, be used, but the switch shown is advantageous because it assures that authorized persons only can control the operation of the device.

A mechanically operated switch 14 is mounted in the case or frame 10 for actuating the alarm circuits when switch 12 is on The switch i4 has movable contacts mechanically connected to a spring such as coil spring 15. Spring l5 is arranged so that it is stressed when switch 14 is open so that its movable contacts are biased for movement to the closed position. Switch 14 also has a movable plunger 16 which is mechanically connected to the movable contacts of the switch. The purpose of this plunger is explained below.

A lever arm I7 is pivotally supported as shown at 18 in case l0 so that it extends through the side of the case at its outer extremity. The inner end of lever 17 is connected to a coill spring 19. The spring is mounted so that lever arm 17 is biased for movement to its normal position as shown in the drawings (note especially FIG- URES l and 4) where itis against stops, bearing against the sideof the case as at 2d.

Lever arm 17 is, of course, movable through a limited arc from the normal position shown to a displaced position against the biasing force of spring 19. When the lever is against stops in its displaced position it bears against the inner end of plunger liti. In this position, the plunger I6 is displaced so that the movable contacts inside switch i4 are also displaced and held in an opened position against the biasing force of spring 15.

A power supply is provided inside this embodiment so that it is a complete, self-contained unit which does not require connections to an external source of voltage. The power supply may comprise, as shown, batteries 2li-23. 6 volt batteries for supplying direct current to energize the alarm circuits are convenient to use for this purpose because they are readily available in sizes which lit into the space available and because other components for operation on siX volts D C. are also readily available. But other power arrangements may, of course, be used.

operated bell 1l, as mentioned above.

A magnetic relay is mounted in the case at 25. Relay 25 has a coil 2,8 and two pairs of normally opened contacts 25 and 27 (note FIGURE 5 or 6). The coil 28 and switches4 12 and 14 are electrically connected in series forming a lirst circuit. This irst circuit, which may conveniently be considered to be a tripping circuit because it initiates the alarm or annunciating sequence when switches l2 and lid are closed, is also connected to a source of voltage. The source for the rirst circuit may be one of the batteries such as 2l. Contacts 26 of the relay are connected in shunt across switch I4.

A time delay relay is mounted in the case at 29. Relay 29 has a heater element Sil and thermally responsive Contact means 3l. The contact means are adapted to be heated by the heater when it is energized and change position due to non-uniform thermal expansion so as to close a circuit. This is commonly provided by using bi-metallic strips which expand and contract at unequal rates in response to heating and cooling, as is well known. Thermal time delay relays are convenient for use in my invention. They are readily available in many different ratings to suit various voltage, power and time delay requirements and their accuracy and reliability is quite satisfactory. Other types may be used, of course.

The second pair of contacts 27 of relay 25 `and the heater element 3b are connected in series in a second or time-delay circuit. The second circuit is connected to a source of Voltage which may be another of the batteries 22.

The annunciator or alarm means is an electrically The bell 11 and thermal relay contacts are contacted in series in a third or alarm circuit. rThe third circuit is also connected to announcing or sounding an alarm when a member such as a movable panel is displaced without proper authority.

For this purpose, case It) may be mounted on the panel, which may be a door, near its side sothat lever arm 17 extends beyond the edge of the door to engage an adjacent member such as a door frame when the door is closed. With the panel or door closed, the adjacent member or frame as the case may be, kdisplaces lever arm i7 from its normal position shown (FIGURES l and 4) so that it engages the end of plunger 16 next to switch ld. This displaces the plunger, ywhich is connected to the contacts of switch lll, as mentioned, so that the contacts are moved against the biasing torce of spring l5 to their opened position. In this position, thel tripping or iirst circuit is opened and the alarm will not sound.

When the door is closed, say, for the night, the manually operated switch 12 is closed with key 13 and the `key removed. Thus the tripping circuit is ready to be energized if the door is disturbed so as to cause switch 14 to close.

It the door is then opened, lever arm ll7 is removed from engagement with the frame member and rotated about its pivot l to its normal position, away from plunger 16, by the bias force exerted on it by spring 19. When this occurs, the restraint previouslyy imposed on the contacts of switch lid is removed and they immediately move to their closed position in response to the bias force exerted on them by springlS. The 'tripping circuit is then closed and voltage is applied to relay energizing coil 28. When coil 28 is energized, contacts 2d and 27 close.

Closing of contacts 26 short circuits switch 14 so that, once initiated, the annunciating sequence continues irrespective of the position of switch 14 until manual switch l2 is opened. This is necessary because by this time a prospective prowler may already have passed through the door, closing it behind him and causing the tripping means, i`.e., the lever arm 17 and spring 19, to be reset -so that switch 14 is again opened by plunger lo. With this shunt connection at contacts 26, the annunciating sequence is irreversibly initiated as soon as the door is opened and it continues as long as the coil 28 isenergized. Closing of contacts 27 of magnetic relay 25 causes K voltage to be applied in the second or time delay circuit and heater element Sli begins to heat. After the time delay which may be, :tor example, ten seconds, the contact means 3l are heated and distorted sutliciently due to thermal expansion to cause the contacts o the time delay relay to close. When this occurs, voltage is applied in the third or annunciating circuitV and the bell ll rings. The bell continues to ring until someone who has akey arrives and opens the switch l2 so that coil 28 and hence heater Il@ are de-energized. And, of course, when heater Il@ is cle-energized, it cools permitting the contact means 3l to contract so that the alarm circuit is opened.

The purpose of the time delay circuit and relay 29 is to afford an interval of time during which authorized persons who open the door may open switch l2 and keep the alarm from ringing. Thus, for example, upon opening the door for the rst time after the alarm has been set, one has an interval of time in which to reach to switch 14, insert the key and disable the alrm by opening the tripping circuit. As soon as this occurs, even though the annunciating sequence was initiated when the door opened, the heater is de-energized so that contact means 3l begin to contract to their normal or opened position before they have had time to expand suiliciently to close the alarm circuit, and the alarm is not sounded.

I have found that a ten `second time delay is usually sucient for any person who knows the location of the alarm and who has a key to reach to it and turn it off before the bell rings. But, of course, other intervals oi time delay may be used.

In FIGURE l, switch t4 is on When lever 17 is vdisplaced to bear against plunger le, very little plunger motion is sufficient to open this switch and the switch may then be considered to be very nearly on For a situation Where the alarm isused, for example, in a *structure where there is a large amount of vibration during normal working hours, it may be desirable to provide means for moving switch ld to a positively determined oli position so that the annunciating sequenceA is not inadvertently initiated.

This may be obtained by providing a toggle arrangement in switch la. That is, the contacts in switch le and the biasing spring 15 may be arranged to operate about a toggle axis, as is well understood, so that the contacts may be moved to a distant o position and held in that place by the same spring l5 until they are again moved back to the on position. Then, addition of a handle Zd extending from plunger lo to the outside of case l@ permits manual control of switch i4.

This arrangement may also be desired, for example,

where only supervisory or guard personnel are permitted to carry keys for switch l2. With handle 24,1an authorized workman, who is permitted to carry only a key to the door or panel on which the alarm may be mounted,

during the time delay period and the workman does not have to wait for a person with a key ll3 `in order to keep from setting off the alarm.

The description of operation which I have set forth has been referenced to the embodiment of FIGURES l-4 and to a wiring diagram for that embodiment in FIGURE 5. A general schematic diagram showing the electrical arrangement for my invention is provided in FIGURE 6. The operating description above applies also to FIG- URE 6 in which dashed outlines are shown to indicate generally the location of switch means 14, magnetic relay means 26, time delay relay 29 and the annunciator or alarm means lll. i

The alarm mechanism of my invention has many applications for monitoring and announcing relative movement between two members. It iscompact and easily installed. It is completely self-contained and installation requires no modifications to existing structures or electrical systems. External electrical circuits arenot required and the electrical system of my invention istherefore not accessible for tampering so that the alarm cannot be disabled-by any individual having knowledge of remote, possibly unprotected, locations of electric circuits or power sources. It may be constructed of readily available standard commercial components so that its cost is low. It is not necessary to have skilled electrical tradesmen install my invention because installation is a simple, completely mechanical procedure. All is required is, for example, a screw driver and a few screws. And my mechanism need not be considered as a device for permanent installation, if the user has but a temporary security situation at a particular location. After that situation has ended, the alarm may be readily removed to a new location.

I have disclosed and described my invention with detailed reference to a particular embodiment thereof. It is to be understood that changes and departures from the embodiment may be made without departing from the spirit and scope of my invention. The scope of my invention is defined by the claim which follows.

I claim:

A self-contained alarm mechanism adapted to be supported adjacent to a member for announcing relative movement between said mechanism and said member, which mechanism comprises, in combination:

a case;

at least one source of voltage supported insaid case;

tripping means having a lever arm pivotally supported in said case for limited angular movement between a normal and a displaced position7 said arm extending through said case and engaging said member in said displaced position, and first biasing means mounted in said case and connected to said arm urging the same to said normal position;

first circuit means connected to one said source and including, in series,

rst switch means adapted for manual operation and second switch means having a pair of contacts adapted for movement between opened and closed positions, second biasing means connected to said contacts and stressed to urge said contacts to said Cil d closed of the positions and a movable plunger connected to said pair of contacts and extending from said second switch means a distance suilicient to be engaged by said lever arm when said lever arm is moved from said normal to said displaced position and hold said pair of contacts against said second biasing means in said opened of the positions; magnetic relay means having a coil connected in series with said first and second switch means in said irst circuit means and first and second pairs of normally opened contacts, said first of the pairs being connected in shunt across said second switch means;

time del y relay means having a heater element and Contact means supported adjacent to said element and responsive to heating by said element for closing;

second circuit means connected to one said source and including, in series, said second of the pairs of normally opened contacts and said heater element; and,

third circuit means connected to one said source and including, in series,

annunciator means and said time delay contact means,

said annunciator means comprising an electrically operated bell, said source of voltage comprising at least one dry cell battery and said plunger having a handle disposed thereon Aand extending to an accessible position.

References Cited in the file of this patent UNITED STATES PATENTS 584,463 Creelrnan June 15, 1897 1,461,294 Simpson July 10, 1923 1,685,329 Lynch Sept. 25, 1928 2,250,828 Foss July 29, 1941 2,460,495 Elrick Feb. 1, 1949 2,701,874 Mears Feb. 8, 1955 2,724,823 Toepfer Nov. 22, 1955 3,011,163 Britt Nov. 28, 1961 FOREIGN PATENTS France May 7, 

